Stencil sheet



Patented Nov. 17, 1925 UNITED STATES PATENT OFFICE.

RICHARD LANT, OF VIENNA, AUSTRIA, ASSIGNOR TO WILLIAM. KORESKA, OF

VIENNA, AUSTRIA.

STENCIL SHEET.

' No Drawing.

To all whom-it may concern:

- Be it known that I, RICHARD LANT, chem.-

ist, a citizen of the Republic of Austria, re-

siding at Gusshausstrasse, Vienna, IV, Austria, in. the county ofVienna and State of Austria, have invented certain new and useful Improvements in Stencil Sheets, of which the following is a specification.

My invention relates to stencil-sheets of the type commonly used for autographic and typewriting duplication andparticularly to stencil-sheets consisting of a fibrous and porous base coated or impregnated with some substance impermeable to the ink, which coating, for the purpose of preparing the stencil, is removed by the pressure of the stylus or by the impact of the types of a typewriter thereon on the places struck by the type or stylus, so that the ink roller or the like, through these openings liberated from th impermeable substance and forming the otters, can deliver ink to a sheet of paper laid under the stencil. Such stenoil-sheets are generally made of open porone material, such as Japanese paper, coat:

ed with a wax-like material, such, for example, as paraflin, or with a dry-hygroscopic compound of coagulated protein, such as gelatine combined with a suitable tempering agent. The wax-coated sheets have the most disagreeable drawback of being exceedingly brittle, so'that in preparing the stencil they are easily injured and that even the finished stencil requires most careful handling. The

stencil-sheets coated with coagulated rotein are not brittle and offer a consi erably greater resistancerbesides that the copies made with the latter are sharper and more uniform. But their use is on the other hand more tiresome owing to the circumstance, that in order to adapt the sheet for making the stencil by pressure (as, for instance, by

the impact of the types of atypewriter), it

Application filed November 16, 1922. Serial No. 601,410.

render the coating more supple and therefore a smaller quantity of the oil is sufficient for obtaining the desired propertiesl Instead of tallow anyother normally solid fatty substance of mineral, vegetable or animal origin may be used, as for instance the fatty acid of cocoanut-oil, parafiine residues and the like.

- The coating can be made of inorganic or organic esters of cellulose (or of oxy-cellulosev or hydro-cellulose) or hydrated cellulose obtained in the manner known per so from solutions of cellulose or cellulose esters by means of a suitable precipitating bath. Furthermore, the coating may include a mixture of esters and of hydrated cellulose,'such as is for instance generated when nitro-cellulose is partly denitrated.

The substance or the mixture of substances -to be used for the coating is preferably dissolved in a volatile solvent and the coating of the base orous, fibrous paper sheet) effected by dipping the latter into the solution or by spreading the solution on the sheet by means of a brush or the like. The choice of the solvent de ends on the nature of the substance to be dlssolved. If, for instance as the normally solidfatty substance to be added to the cellulose ester besides the oil, hydrocarbons or fats are chosen the solvent may be tetrahydronapht-aline (tetraline) or dekahydronaphtaline (dekaline). If for the same purpose fatty acids or substances soluble in a mixture of ethylic ether and alcohol or in amylacetate are chosen, these solvents may be used. In cases where the coating material consists of cellulose esters or the like the solvent isallowed to evaporate after the coating is applied, and the stencil-sheet is then ready for use. To produce a coating which consists wholly or partly of hydrated cellulose, the mass put on the base must be treated thereafter w1th a suitable precipitating liquid. Thus, for

example, a coating made of nitro-cellulose, ma be rendered softer as well as more hmp an pliable by partly denitrating it A racticable formula for use in compoun ing such a coating (but to which the invention is not limited) is 400 grammes of nitro-cellulose, 800 ammes of castor-oil, 1000 grammes of ta ow, 10 litres of amylacetate. To this may be added if desired, a suflicient quantity of a suitable colouring solution.

The stencil-sheets made according to this invention ofier the same advantages as the protein-coated sheets in comparison with wax-coated sheets, but are superior to the protein-coated sheets by the fact, that for preparing the stencil they can be used in a perfectly dry state.

I use the term derivative of cellulose to include not only one determined derivative, but also a mixture of several derivatives.

What I claim is:

1. A stencil-sheet adapted for stencilization by pressure, comprising a base of open porous material with a type-impressible coatin including cellulose derivatives, an oil an tallow.

2. A stencil-sheet adapted for stencilization by pressure, comprising a base of open porous material with a type-impressible coating including cellulose derivatives, castor oil and tallow.

3. A stencil-sheet adapted for stencilization by pressure, comprising a base of open porous material with a type-impress'ible coating including nitro-cellulose, castor-oil and tallow.

4. A stencil-sheet adapted for stencilization by pressure, comprising a base of open porous material with a type-impressible coating including about 18.18 parts by weight of nitro-cellulose. 36.37 parts by weight of castor-oil and 45.45 parts by weight of tallow.

5. A stencil sheet capable of being stencile'd by normal action of the type of a typewriter, or by a stylus,.comprising a sheet of open porous material'coated with a perma nently homogeneous mixture consisting essentially of a cellulose ester, a liquid fatty oil and a normally solid fat, the amounts of said cellulose ester to said liquid fatty oil being such that from a mixture of these two components only, applied to said sheet, separation of oil would occur, and the amount of said solid fat being suflicient to prevent such separation, and being in excess of the amount of liquid oil. a

6. A 'product as covered in the claim last above written, in which the liquid fatty oil is castor oil, and the solid fat is tallow of animal origin.

7. A stencil sheet capable of being stenciled by normal action of the type of a typewriter, or by a stylus, comprising a sheet of open porous material coated with a permanently homogeneous mixture consisting essentially of a cellulose derivative, 21 greater amount of castor oil and a still greater amount of a hard fat.

8. A stencil sheet capable of being stenciled by normal action of the type of a typewriter, or by a stylus, comprisingyar sheetof open porous material coated with a permanently homogeneous mixture consisting essentially of about one part of a cellulose ester, about two parts of castor oil and somewhat more than two parts of a hard fat.

In testimony whereof I have allixed my signature.

RICHARD LANT. 

